1. Technical Field
The present disclosure generally relates to the field of self-propelling robots. More in particular, the present disclosure relates to a working apparatus for a limited area.
2. Description of the Related Art
There are known self-propelling robots, such as for example lawn-mowing robots, pool cleaning robots, vacuum-cleaner robots or floor-washing robots. These robots are capable of moving autonomously by virtue of a rechargeable battery, which has the purpose of supplying power to the electrical and electromechanical devices present inside the robot, such as, for example, motors for moving wheels and blades, sensors and data processing units.
When the battery charge level is too low, the robot moves automatically until reaching a base recharging station, wherein the battery can be recharged.
Similarly, when the robot has completed the working cycle (for example, lawn mowing, pool cleaning, vacuum cleaning or floor washing), the robot moves automatically until reaching the base station, such as, for example, a point for draining the filter.
International patent application WO 03/104909 discloses an electronic navigational control system for a lawn-mowing robot. The system comprises a smaller inner conductor loop 3 and a larger outer loop 2 connected to an alternating current generator 1 (see FIG. 1), wherein the surface defined by the outer loop 2 corresponds to the working area of the self-propelling device. In this manner, the inner loop 3 and the outer loop 2 generate respective magnetic fields. The lawn-mowing robot includes a receiver 14 for the magnetic fields (for example, one or more conductive turns wound around a magnetic core) and uses the magnetic field received from the outer loop 2 and the inner loop 3 to return to a recharging station 3.
The Applicant has observed that said electronic navigational control system for lawn-mowing robots has the following disadvantages:                it is too complex, because it requires the use of two current conductor loops;        the time it takes the lawn-mowing robot to return to the recharging station 3 is too long;        the lawn-mowing robot can reach the base only by following a preferential direction, in particular by following the direction in which the magnetic field is zero (see line 55 in FIG. 12);        it is too expensive.        